Contrail 75mm Fit, Form & Function

For those of you who own and shoot the 75mm Contrail motors, which motor do you like the most? Or better yet, which is the most versatile between the 1400cc and 2050cc systems? I not referring to propellants or relaods, but over-all motor design for fit form and function. Of course if want to say which reload(s) are fav's, by all means picture up!

A club member has the Contrail setup. He has flown it a couple of times. His one issue is that the hardware is very heavy for the impulse. They fly well though.

Edward

Edward is right,

the small combinations are heavy related to the impulse but practical in length. Nevertheless I love the black smoke K888 with the 2 liter tank, just great power for the 600-1200 meter range with 12 to 15 kg rockets...I flew so far only one big 3L case with a L1222 sparky I. Just fantastic push, unbelievable thrust but poor picture compared to the sparky II fuel used in the 54mm, which is a real crowd pleaser. Now I know from this week (!) that the Sanders are thinkin about bringing the sparky II also in the 75mm..this is going to be a crazy reload..I get the first 10 I promised you *lol*...

Well I tested also the gold fuel...nice yellow flame but not much smoke compared to the the BS. Solid performances too. Generally the hybrids do not smoke much compared to AP..but who cares..Falcon 9 also do not smoke ;-) ...but hybridz scream so much!
Finally I would really say that I feel the performance indicated are all wrong...I mean too low...I cannot believe it when you see the push of the motors at start, it just dry you socks immediately..

Lovely side effect on the 75mm modular: so easy to clean as you do not touch the tank..just the combustion chamber and get ready to rumble gain...Other pretty nice detail: you get 2 (!) anchor points for 5/16" screws/eye bolts on the top of the tank. This makes your life so much easy for the construction. You can even modify it according to your needs...
Last point: the motors are 100% compatible to the 75mm aeropacks, what else do you want? Yes of course same impulse but shorter..in this case wait for the 98mm monotubes to come...they will surprise you..

I LOVE THEM!!!

But I know the 75mm monotubes are coming now in 3 and 4 foot length for a solid K-M range impulse at much lower weigt, means better performances... this is going to be a great summer!!

Denis

I haven't seen an update on the monotubes for a while.

Gerald

Gerald, you know that contrail is not really world famous for marketing announcements *lol*...I talked to Thomas Sanders earlier this week and he confirmed they will deliver this year first 75mm monotubes. Obviously the response on the 98mm was not that strong so it will be skipped (unfortunately for me!). Thomas was very confident to get it certified soon by TMT so it could be use in regular TRA launches and not only EX. Obviously TNT had difficulties in the past to build the appropriate test and measurement equipment after their move to another location. In addition Thomas told me he fond a partner with appropriate tools to machine the tubes without a mil run, this shall also be a benificial factor to us. Last positive info they think to deliver the sparky II fuel to the 75mm series, which is really great for the launches...

Now let see what really happen...

legranddudu said:

Gerald, you know that contrail is not really world famous for marketing announcements *lol*...I talked to Thomas Sanders earlier this week and he confirmed they will deliver this year first 75mm monotubes. Obviously the response on the 98mm was not that strong so it will be skipped (unfortunately for me!). Thomas was very confident to get it certified soon by TMT so it could be use in regular TRA launches and not only EX. Obviously TNT had difficulties in the past to build the appropriate test and measurement equipment after their move to another location. In addition Thomas told me he fond a partner with appropriate tools to machine the tubes without a mil run, this shall also be a benificial factor to us. Last positive info they think to deliver the sparky II fuel to the 75mm series, which is really great for the launches...

Now let see what really happen...

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This is good info legranddudu, thanks you. I believe that Westcoast Hybrids and Skyripper both tried their hand at 75mm monotube hybrids but folded the business before completion of the projects. I hope that Contrail does well with these.

I fly mostly my 3200cc tank. Heavy but a great system. Also looking forward to the monotube 75mm system for the weight reductions for the smaller loads and I will be holding out on the 98mm until the monotubes come out for sure. I'm disappointed as well that the 98mm's will not be coming anytime soon. The L2525 from 100m makes you say WTF was that! It's loud and in your face!

Like Denis I also fly the K888 once in a while. Nice motor as well.

75mm K888 preparation at 1am in the morning ...you can improve your german *lol*

[video=youtube_share;LRCArAFhbso]https://youtu.be/LRCArAFhbso[/video]

[video=youtube_share;EnlEE_DaBck]https://youtu.be/EnlEE_DaBck[/video]

[video=youtube_share;UG6-m4aC2K8]https://youtu.be/UG6-m4aC2K8[/video]

Wow, even began to remember my Volkshochschule lessons from when I lived in Oppenweiler (northeast of Stuttgart)...

legranddudu said:

Lovely side effect on the 75mm modular: so easy to clean as you do not touch the tank..just the combustion chamber and get ready to rumble gain...Other pretty nice detail: you get 2 (!) anchor points for 5/16" screws/eye bolts on the top of the tank. This makes your life so much easy for the construction. You can even modify it according to your needs...View attachment 120765

Denis

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In a larger than 75mm airframe the two attachment points is nice but in a minimum diameter they are too close to the outside so I made an adapter to put a single eyebolt in the middle. A little more weight but at that point what's the difference?

Jason

legranddudu said:

75mm K888 preparation at 1am in the morning ...you can improve your german *lol*

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Excellent video Denis... although I only recognized a few words, I could easily follow along. Definitely have alot of fiddle factor with these motors. Do you ever get to prep at the field for multiple flights, or are these "night-before-preppers" to get one shot in on the day?

From what I gather from form, fit and function; the 75mm line is heavy, fiddle factor or prep time is extensive, and all of it worth the end result (flight)...

I like that the motor vents from bottom... I like the assembly with socket head cap screws or better said; the lack of snap rings.

Do all of the tanks come without anidization? I would prefer they were all black... mainly asthetics.

*SOAPBOX ON*

I wish a long, long time ago when standards were being created that 75mm motors would have been left at 3" OD, and 98mm motors would have been left at 4" OD. I can only imagine the machining time and cost of custom runs of tubing up to this point are far more expensive than having the motor mount tubes made bigger to accept them.

*SOAPBOX OFF*

I've considered making 4" mono-tube hybrids and selling compatible motor mount tubes, but then APCP was de-regulated and the market shrank considerably.

Edward

I have been waiting for the Contrail 75mm monotube L-M sized impulse to become available and certified. Any date on availability, cost weight etc.?

Hopefully Tom Sanders can give us the proper answers soon.. I will give them a motivation call when I am back from China..

any updates on the 75mm (or 98mm) Monotubes?

I recommend the 3200cc tank with 12"combustion chamber and medium nozzle.

karlbaum said:

I recommend the 3200cc tank with 12"combustion chamber and medium nozzle.

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What have you flown with this combo? I was looking at getting the next size down, but was disappointed that it was only good to a K-class motor. I was contemplating getting the Dominator 4 and flying it on the Contrail 75mm...

karlbaum said:

I recommend the 3200cc tank with 12"combustion chamber and medium nozzle.

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An update to my last post; I had a nice long talk with Tom Sanders of Contrail yesterday, and he also recommended the same motor combination. The 3200cc with the medium length chamber and medium nozzle. He also recommended to pick up the slow nozzle to open up a decent range of reload options. My path forward is stating to clear a little.

Johnnie,

happy to read you could touch base with Tom! He and his father are such great persons...
My personal recommendation for a 75mm is a little bit different: I would go for the 2 liters + 3 liters tank with the 10 and 12 inches chambers, accompaign with theslow and medium nozzles.

It is certainly more expensive but a great combo in the medium K range (for the shorter shots in windy days or in small fields), also with the great K888 reload (10 inches chamber, medium nozzle, incredible power) but also the large 3 litres tank with the marvelous M711 black smoke (12 inches & slow nozzle) or the L800 black gold, both moon burners...and if you have already the medium nozzle you can run the M-Black Smoke at the next speed: 1450...

But do not forget that both are looonnngggg casings and this will force you to build differently your rockets and rethink your deployment designs...but such great motors...never had one sole defect with the 75mm ...

Tom was very helpful in shedding some light on options that lay before me. More importantly, he assured me that Contrail is here to stay for the forseeable future... this was a huge relief to me.

I do not have all of the details laid out yet, but here is an option I am considering:

Ordering either the complete 75mm contrail system, or just the complete [2050 / short / slow] and the [3200 / medium / medium]

The vehicle of choice would be the Dominator 4 (not the 4R)

Reloads I am looking at are the K777; K300; L369 and the M1491 After that, I would be developing research laods for the prospective hardware.

As for GSE... Since I would probably be the only hybrid flier in the great state of Alabama, I was looking at getting the Black Dog GSE or Pratt Hobbies GSE... I have owned a GSE outfit from Pratt in the past, so I am familiar with it... but Black Dog has some very nice options as well.

I feel pretty good about this so far... must research further... and by the way, your video channel is a HUGE benefit to anyone wanting to see a Contrail in action... I really like them!

legranddudu said:

Johnnie,

happy to read you could touch base with Tom! He and his father are such great persons...
My personal recommendation for a 75mm is a little bit different: I would go for the 2 liters + 3 liters tank with the 10 and 12 inches chambers, accompaign with theslow and medium nozzles.

It is certainly more expensive but a great combo in the medium K range (for the shorter shots in windy days or in small fields), also with the great K888 reload (10 inches chamber, medium nozzle, incredible power) but also the large 3 litres tank with the marvelous M711 black smoke (12 inches & slow nozzle) or the L800 black gold, both moon burners...and if you have already the medium nozzle you can run the M-Black Smoke at the next speed: 1450...

But do not forget that both are looonnngggg casings and this will force you to build differently your rockets and rethink your deployment designs...but such great motors...never had one sole defect with the 75mm ...

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Johnnie not sure about the combo you mean but yes, by choosing the 2 liters and the 3 liters tank in combination with 12" and 18" plus slow and medium nozzle...you can't do wrong...
Remember, basically each grain, featured for a particular chamber length and tank combination can be run at various speeds, just by changing nozzle and injectors accordingly.

For example the L369 sparky turns into a L1222 or the K404 into a K777 just by exchanging the 1/8" presslocks against 3/16th and the medium instead the slow nozzle...this gives you a great flexibility for each grain to choose out of 3 speeds (there is also a fast nozzle), depending on wheather/wind or rocket weight... I wish AT or CTI would deliver such a flexibility.. Personnaly I would not go for the sparkies in 75mm, with much respect for contrail. They are not really comparable with incredible sparkies "2" available in 54mm or 38mm... but in 75mm I would strongly recommend the black smoke for heavy thrust (and a nearly red flame and black smoke!) or the black gold (less push but lovely yellow flame and white smoke). I dream from sparky "2" in 75mm but Tom said it is simply too expensive to produce...

Next you will really enjoy the easy way of mounting and maintaining the motors..just a few tools, very solid and precise machining. just do not forget to grease everything really a lot...your motor will thank you...and you will definitely need to buy the anchor point(s) (forged eye bolts 3/16th) for the top of the tank (also available at McMasters for you, the bastards refuse to sell to Germany!). Just screw it and attach your chutes...or recovery devices..so simple and so safe...if you need I have engineered "bones" of steel that fit above the 2 holes so you can attach more devices...or ask Jason, he posted a very nice anchor point solution in this thread just above...very lovely indeed.

Now let's talk about GSE's... of course you can build your own with little knowledge in electronic and hydraulic. BUT if you want to fly ..go for one of the 2 you mentioned... Personnaly I was hesitating between the 2 vendors but Doug Pratt made me such a great offer ...I could not resist. I believe that Black Dog may be of more valuable materials but the cheap and light red plastic box from Doug works just well...So I went for the full specs GSE from him, oversize solenoids, all options, etc... One custom made change for me: the remote control device. I asked for a long distance one. I can run it with 100 yards of cable! You will love the security distance and the chance to see your bird flying from a more normal angle... His GSE remote control unit offers you all comfort you can ask: fill & dump remotely, security key to avoid hazardous manipulations. It is NOT radio controlled but...you can not disturb the signal with a cable...just a mess to roll each time *lol*..the price for more security... His GSE runs with 12 or 24v depending on your ignitors. here we run 12v, just one battery. By the way, do not "save" at the wrong place. Buy a good solid maintenance free car battery. The solenoids need a lot of current to work properly. I made once the bad experience...

Now the only critic on Doug's GSE was the "cheap" fill line. I simply believe it was not appropriate and after les than 10 starts it just exploded...now I have a german hydraulic cable, heavy rubber with Steelflex and teflon tube inside. Just "panzer"-grade.. even when I fill the biggest tank..the cable just do not move a centimeter from the place...Now I heard from Doug he changed his cable after I complained..now I do not know how are the new ones...I loved Doug customer service, such a friendly supplier, always happy to help.

Now one last idea. if you buy a stock dominator from Gary you may have some headache with the booster length (40"/53"!!!)and recovery deployment design that may move to the NC...not sure you can run that....so ask Gary, he may cut you the nice bird just as long as you need...certainly at costs but I learned from my last experiences that Proline is a great supplier with very reasonable pricing for not really reasonable customers like you and me *lol*...better ask before too late!

Hope this helps

Denis

Mr Kramer... Contrail says the 75 monotubes are available right NOW in 28" 36" 48" and even 60" (!!)... but lead time approx 4 to 6 weeks (custom order).
The 98mm are NOT available at present *tears*...

Pricing has not changed since my last post as I understand Tom:

Pricing is as follows in USD:
75mm Monotubes:
28inch Tank: 175.00
36 Inch Tank 215
48 Inch Tank: 270
60 inch Tank: 325

Bulkhead: 75
Nozzle: 100
Liner (Needed for Support of Grain): 35
Nozzle Washer: 20
Snap Ring: 3.50
Thrust Ring (External): 12.00
Injector: 85.00

The 98mm Pricing is
36 Inch Case: 300
48 Inch Case: 450
98mm Bulkhead: 75.00
Nozzle: 150
Injector: 95
Liner: 45.00
Nozzle Washer: 25.00
External Thrust Ring: 18.00
Snap Rings: 5.00

The 75mm Motors will range from K-M
98mm Motors from L-N

Cost on the Grains will be similar to the "Legacy Motors" (They use the same fuel Grains). Never changed since 2006!!!!
75mm = 95 Dollars
98mm = 180 Dollars (Sparky Motors excluded).

Of course these are international prices all taxes, transportation, customs, etc.. on top...

kramer714 said:

any updates on the 75mm (or 98mm) Monotubes?

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DRAGON64 said:

What have you flown with this combo? I was looking at getting the next size down, but was disappointed that it was only good to a K-class motor. I was contemplating getting the Dominator 4 and flying it on the Contrail 75mm...

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I have flown the Polecat 7.5 inch V2 rocket with the M1491 and M711. I have also have made a couple of custom rockets for it. The slower nozzle is fun but you are limited on takeoff weight especially with the sparky motor.

Thanks Denis, your experience with Contrail is proving to be very valuable.

I have talked with Black Dog rocketry, and got some preliminary pricing. I have not heard back from Pratt Hobbies yet... I understand that his day job has been quite busy for him lately. I have owned the Pratt Hobby system, and it was pretty straight forward, and less cumbersome than the olf HyperTEK system. Like you, I had a custom fill line made up for $30, and all was good. However, the telephone line turned out to be not-so-rugged, and started to fail... I ultimarely sold the system when I walked away from Hybrids in 2005. I really like the looks of the Black Dog Rocketry GSE. Their GSE is about $200 more than the Pratt system, but appears to be quite rugged... ultimately my budget will decide, but if I AM THE ONLY hybrid flier in the great state of Alabama, then I need a system that wil not fail me...

Regarding Sparkies... I'm not a special effects fan, other than I like watching someone fly them so I can "Ohhh! Aahh!" I mainly chose the L-class sparky as an option because of the 10-second burn... I like long burn motors. If I can manage this come back my way, I will more than likely I will not get the sparky motor. I will opt for the other formulas for power and burn time.

Karl, I would probably trade out the L sparky for the M711... I like the profile of this motor... and the M1491. I'm due for a rematch with a 75mm M-class hybrid... here is video the last time I flew a large Hybrid... note here, that Tom Binford shot the video, and all rights go to him... I play it from time to time as a reminder... That I need to finish this!

https://www.youtube.com/watch?v=ckohj0VVKZU

Here is the shortened version with motor kick out...

https://www.youtube.com/watch?v=VMragSB8kAI

Black Dog (Ron) makes some serious hardware, well built and rugged. I have seen lots of equipment from them, I recommend Black Dog highly!

Mike K

Black Dog Rocketry makes very nice GSE. I highly recommend it. I don't know if Ron still sells it but I thought the GSE 1 looked very nice.

Karl

The description I received from Ron by email makes the product very enticing, and the picture on his website only enhances the urge to pull the trigger and get this product. Getting closer now!

https://blackdogrocketry.com/?page_id=112

DRAGON64 said:

The description I received from Ron by email makes the product very enticing, and the picture on his website only enhances the urge to pull the trigger and get this product. Getting closer now!

https://blackdogrocketry.com/?page_id=112

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i would like to know what solenoids he offers? what size/specs? does it fit to the largest contrails? remember you need to feed them with a lot of nitrous in very short time....

legranddudu said:

i would like to know what solenoids he offers? what size/specs? does it fit to the largest contrails? remember you need to feed them with a lot of nitrous in very short time....

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Black Dog Rocketry does not use the beefy solenoids like those offered (as an upgrade) at Pratt Hobbies. The Black Dog Hybrid GSE comes with the standard nitrous solenoid and the system has the solenoid saver circuit designed in.

I have used Ron's GSE at ROC launches on a Hypertek M with a 5400 cc tank, that's LOTS of nitrous. Worked fine, filled quick.