Estes 1250 Interceptor converted to R/C RG

[burkefj]

Since I've done an Estes Interceptor E conversion to RC RG, and I'm working on a 4" upscale, I found out that I could get the 1250 original interceptor from amazon for $21.95 delivered, so I thought I'd try to do a mini R/C RG version on that as well. I've got my wings and fins cut out of 6mm depron, and done the mass balancing sims and CG calculation. Right now it looks like it will work, remains to be seen how much the cone weighs and whether I will need the tail cone for balance or not and whether I'll do foam wingtip pods or use the original kit plastic items, it all depends on the weight overall.

Also found my original picture of my Interceptor E conversion which did use the tail cone but not the tip pods...that's what I eventually kitted but using the Cosmic Interceptor kits they were closing out for a while....

 

[neil_w]

"I regret that I have but one Like to give to these Interceptor posts".

 

[burkefj]

So I opened up the kit and weighed everything and the antennas were 1.2 g each and the wingtip pods were 5.9 per side which was a little bit heavy. So I decided to just glue one half of a wingtip pod onto a piece of 6 mm depron and then cut it out and sand the depron round. The depron will glue directly to the straight wing tip, that got each side down to 3.4 g each. I cut the antennas off at the point where they go into the fatter base which is supposed to slip over the thin wood stab tip and then grooved the top of the foam fin and glued the antenna in. It's a little bit shorter but less likely to snag on something and that only added 0.5 g per fin.

I trimmed off most of the nose cone shoulder and base to save a little bit of weight, and cut a slot in the rear tail cone so it can clear the engine Hook when you bend it to get the motor out.

I proceeded to wrap the brown cardboard tube in white vinyl and then cut the slots for the wing and tail and cut the rail button holes. The white vinyl added 5 g but it meant that I wouldn't have to paint the body tube.

I installed the wing after putting the rail buttons in and then the vertical tails then I assembled the motor mount basically as per spec and then notched the forward centering ring to clear the through the wall tabs that I have on the vertical fins and installed it.

I stuck everything in and it looks like I'll be able to balance without adding any weight in the nose or the tail and should come out right around 5.75 Oz ready to fly which is a little heavier than I like but not bad for using some of the plastic parts. It'll be about the same weight as my mini colonial viper that I did which still flies fine.

If anyone's wondering why I use depron I weighed all of the balsa wood parts that came in the kit and they weighed 24 g. Given that the wing is at least three times the area of the stock kit wing that would mean I'd be close to 75 g if I was using 1/8" balsa wood. The depron
wing and tail surfaces combined with the carbon spar is only 20.5 g total.

 

[burkefj]

As a side note for cutting the wing slots I used my piece of angle aluminum and normally I have a piece of long coupler that I insert to back up the tube when I cut the slots. In this case I didn't have anything for bt55 but I did have some 29 mm motor mount stock and it turns out that if you slit one piece and slide it over another it's a perfect fit inside bt55 to support it for cutting slots.

 

[burkefj]

My estes R/C conversion 1250 interceptor nearly done, reinacting a 1976 photo of me working on my first interceptor 46 years ago...

 

[boomtube-mk2]

Since I've done an Estes Interceptor E conversion to RC RG, and I'm working on a 4" upscale, I found out that I could get the 1250 original interceptor from amazon for $21.95 delivered, so I thought I'd try to do a mini R/C RG version on that as well. I've got my wings and fins cut out of 6mm depron, and done the mass balancing sims and CG calculation. Right now it looks like it will work, remains to be seen how much the cone weighs and whether I will need the tail cone for balance or not and whether I'll do foam wingtip pods or use the original kit plastic items, it all depends on the weight overall.

Also found my original picture of my Interceptor E conversion which did use the tail cone but not the tip pods...that's what I eventually kitted but using the Cosmic Interceptor kits they were closing out for a while....

Seriously dude!
Don't you have anything better to do with your life than to build these incredible radio-controlled rocket glid . . . on second thought, I can't find any fault with that.
Never mind.

 

[burkefj]

Apparently I don't

Seriously dude!
Don't you have anything better to do with your life than to build these incredible radio-controlled rocket glid . . . on second thought, I can't find any fault with that.
Never mind.

 

[burkefj]

Some more Glam shots, pretty much complete except for some stickershock markings to finish it off, the water decals won't stick to the foam/vinyl wrap that well and I prefer vinyl anyway.
I added wing walk markings on the strakes since they are oversized and looked a bit plain.

 

[burkefj]

Here is both my Interceptor E and 1250 Interceptor conversions on their maiden flights today...

 

[neil_w]

Beautiful. What a sky!

 

[burkefj]

Yes, it was overcast and lighty snowing this morning then turned into this, I love cold days, it really gives a lot of nice white dense smoke on boost to contrast the blue sky! Reminds me of those videos from the ground of the X planes rocketing skyward...

Beautiful. What a sky!

 

[tab28682]

Frank’s hit parade just never ends…

 

[cls]

gosh... the stuff of dreams! thanks

 

[burkefj]

That was fun and I have a second kit and decals from stickershock, on this second one I'm going to move the wing forward so that it isn't as nose heavy, lose the dorsal fin antennae, tail cone and motor hook and see if I can drop a half an ounce to the overall weight and get a little more glide in this new version

 

[neil_w]

lose the antennas

Good thing there was an AED handy when I read that.

 

[burkefj]

So took an hour yesterday and my second interceptor kit and did some simulations for balance point and built a second version moving the wing forward a half an inch and that allowed me to remove the motor hook, the antennas, the tail cone and the blow molded plastic wingtip pods and substitut profile foam tip pod versions like I used in my other versions. Balance came out perfect by moving the battery forward slightly and removing the receiver casing. I did wrap the body tube in white vinyl like the first version before I started assembly which only adds 5 g but you could use a white body tube and skip that part if you wanted it even lighter. This version only weighs 5 oz ready to fly as opposed to 5.75 Oz with the version that used more of the kit parts. That's 15% weight reduction that's pretty significant.

I got the text, star and bar and stab decals from sticker shock today and applied them to both models and I think they look great. I'm glad I did the one with the kit parts since I really wanted to have those little details but I think the second one will be a little bit nicer flyer

 

[burkefj]

New lightweight one flew great, perfect trim and glide, got about 15 seconds more out of it and higher boost.

 

[burkefj]

I will be offering a short kit for this conversion, just add your interceptor kit.

 

[tab28682]

I will be offering a short kit for this conversion, just add your interceptor kit.

I am at the local hobby shop that is having, sadly, a going out business sale.

I am also quietly cursing Frank under my breath, as the shop had a 1250 Interceptor kit going at 50% off…

Frank will be getting my short kit order later today….

For those of you that live in the DFW area and those that have visited local area hobby shops, our excellent Roy’s Hobby Shop is having the last day of a going out of business sale. They were a fantastic shop that I have patronized for over 40 years. A very sad day.

 

[burkefj]

Hey glad to help you should really get two I know Dave Schafer was asking if I was going to make a conversion kit...

I am at the local hobby shop that is having, sadly, a going out business sale.

I am also quietly cursing Frank under my breath, as the shop had a 1250 Interceptor kit going at 50% off…

Frank will be getting my short kit order later today….

For those of you that live in the DFW area and those that have visited local area hobby shops, our excellent Roy’s Hobby Shop is having the last day of a going out of business sale. They were a fantastic shop that I have patronized for over 40 years. A very sad day.

 

[tab28682]

Hey glad to help you should really get two I know Dave Schafer was asking if I was going to make a conversion kit...

I got the one and only 1250 in the store.

 

[tab28682]

And now my short kit order is in…

 

[burkefj]

I've also released a conversion kit for the Interceptor E and Cosmic Interceptor kits to make the medium sized version of this glider for E-6 motors. You can also provide two ps-II 2" tubes, coupler and an interceptor cone from a trajector if you have that, or use a standard 2" cone as well if you wanted. On the website.

 

[bibbster]

What is your web addy?

 

[burkefj]

dynasoarrocketry.com

What is your web addy?

 

[CalebJ]

All of your designs are beautiful. Some day when I get caught up on my build pile and -far- better at RC flying, I'd love to step across into rocket gliders. Constantly impressed by the flight videos.

 

[tab28682]

Dave Schaefer and I cannot resist Interceptor related RC RG.

Our 1250 semi kits arrived today and now we have the Interceptor E semi kits on order.

Frank is evil and will come to a bad end….

 

[burkefj]

Guilty as charged.

Dave Schaefer and I cannot resist Interceptor related RC RG.

Our 1250 semi kits arrived today and now we have the Interceptor E semi kits on order.

Frank is evil and will come to a bad end….

 

[tab28682]

Guilty as charged.

The source of much temptation in this niche of our hobby…

 

[tab28682]

Frank, I am dropping off some of the molded wingtips for both the 1250 Interceptor and the Interceptor E at a local vacuformer who does a lot of RC aircraft parts. Going to see if he can do some super light vac formed wingtips. I predict they will be a good bit lighter than the factory parts.

Will report back.