Greg G

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While I am updating this thread, here is a little recap on the prototype. I finished last season with 76 flights on the JetBlast at the Maine Jet Rally. The Last flight of the season was my first deadstick landing. Luckily, I had good speed and sufficient altitude to make it back to the runway safely without incident. The plane glides great with the flaps up and when I was confident to make the runway I selected take off flaps and used them for landing.

I had to send the Rabbit in for service, and it was close to its 25 hour service time anyway. I had the engine upgraded from propane to Kero Start while it was there.


I was also very proud to receive the Best Sport Jet award at the Big Apple Jet Rally in 2013. In 2012 I received a peoples choice award at a full scale airshow in Ocean city, NJ. My kids kinda destroyed that one knocking it off the mantle somehow! Its easier to take a picture and display them here rather than keep them on the mantle! The lovely model is Snickers our Labradoodle.

Greg G

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Hi Brian,
The shape of the tank can make it a challenge to place the cloth, but the lip itself is not too difficult to mold. The only trick is to get thickened resin underneath the sharp corner of the lip and let it gel. After that, the cloth is going to come almost straight out. I trim the wet cloth at least 1/2" beyond the "mold plate". When its 'almost' hard, I trim with a blade flush with the top of the "mold plate".

Boomerang1

Thanks for posting the details on how you make the shiplap joint.

Took a bit of thinking on my behalf but now I get it! John.

TUMBLER

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I should have have not tried to figure it out on a Sunday when my brain wasn't at full capacity. Took me quite a while to get it too LOL

Greg G

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I have not flown the JetBlast very much the last two seasons. Mostly because there are not as many places to fly it in New Jersey, but also because I damaged the nose at one event and damaged the stab at a different event. Both incidents where related to excessive bounce on landing.

The landings where not that bad to have so much bounce, so, I decided to make a drop test rig to see what was really going on on landing.

The test rig has similar landing gear position and CG location as the JetBlast and the weight is similar to the landing weight of about 18 lbs (Low fuel/dry weight).



The rig is suspended from the ceiling at the CG. The drop distance is about 11 inches on concrete.

I have modified the struts in the past by relocating the spring mounting location to have more pre-load (located farther). This first test was with the springs that were used last. The second test was with the addition of rubber bands as decribed in post x above.
Drop 1 https://youtu.be/O0qpn0rxSAI
Drop 2 https://youtu.be/sDH_xSpXb3s

Jetkopter

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Greg , it looks like the gear bottoms out and transfer the energy back in the other direction. Maybe try a progressive spring or dual spring.

Greg G

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The struts tend to over stress the springs pretty easily as the travel is not limited. I added some RC car shocks to the struts. I am not using them with shock oil, but, they are filled with polyurethane foam to dampen the end of travel impact when the struts compress. Drop test Three shows less travel and less re-bound of the struts.

Drop 3 https://youtu.be/dQdJkbrrvGg Note that the videos are in Slow Motion.

Greg G

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I did get to test the strut modification at the Fall Edition of OC-Turbo Fest at the Titusville Airport in PA. The modified struts seem to work well so far as I did not have any bouncy landings.

Jetkopter

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Greg I would try the shock oil, we use it in the skymaster struts. I know I don't have to tell this but hold the plane off before touching down, slower speed and the wing does not want to fly anymore. If your coming in hot and cant go around you can preset the brakes and it wont bounce. I always enjoyed watching your plane fly, reminds me of what a starfire would have evolved into!

George

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It's been a very long time Greg, glad to see you are still at it. I always liked that plane, too bad it was never produced.

Gary Szetlak

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I saw Greg fly this at the last Titusville event, the flights and landings were Super. I saw the bounce landings the year before at Titusville and the change was dramatic. It was nice flying with you Greg! Sweet looking/flying jet
Gary

Kevin_W

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Looks like the struts on a Mig 23 or SU 25. I like it! I bet putting oil in the shocks would be helpful too. You do some excellent work!

Greg G

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Hi Don, I will drop test the struts with oil in the shocks next. Should be fun to compare. The main issue I was trying to improve with these struts is to limit the travel with the shock body. The springs are also on the weak side for the weight of the plane, so even with a moderate bounce on landing, the excess travel over stresses the spring and they take a set and then get weaker for the next landing.... The polyurethane foam in the shocks does add to the spring force which is helpful and it also dampens the impact when the shock bottoms out.

Hi George, good to hear from you. Hope to see you at a Jet Event soon, we just need more of them.

Thanks Gary, Titusville is a great place to fly. I would love to have access to an airport like that closer to NJ.

Thanks Kevin!

melvin

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Hi I just wanted to congratulate you on your jet build! You are one smart guy and your workmanship is top notch! Hope you get many great flights with your new jet

Mel

Jetset

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Like seriously WOW. I am going to try this myself this winter....I can only wish that it turns out as nice as yours! Beautiful!