Mi-24 question

[dov]

Hallo

Front undercarriage:

Does anyone have an idea, why the big hatch in the rear of the undercarriage is not covered?

Or are they just removed?

This is in contradiction to the sowjet aircraft design, where all hatches are closed, just a minimum stays open!

Is anyone an aircraft mechanic on such a helicopter to give us more detailed information?

 

Happy modeling

[Doom3r]

I am not sure if there was such rule for closing everything: Yak-40 had no main gear doors

[Hook]

On the initial Mi-24A variant the nose gear was fully enclosed while retracted. The designers must not have deemed the benefits for the same approach on the D worthy from an aerodynamic point of view. 

 

On some aircraft the wheels extend below the surface to assist in crash landings, but the optics pods under the nose of the D and later would make this an unlikely reason.

 

Cheers,

 

Andre

[HAAFPhot]

It was believed back in the day (least within our Avn intel cell) that the things were so underpowered, transitional take offs and in the main landings were pretty normal and the UC deployed below a minimum airspeed. Might be something to do with that, or simply that locally they were in short supply and felt to be superfluous so not replaced, bit like the original engine cowl arrangement for the Westland Scout. More trouble that it was worth🙄

[GiampieroSilvestri]

The Mil-24D has two Klimov TW3-117A engines with 2200Hp each.The AH-64D Longbow Apache has two engines with 1660Hp each that in case of emergency can reach 1940Hp for a maximum of two minutes.

 

Saluti

 

Giampiero

Edited October 10, 2022 by GiampieroSilvestri

[exdraken]

9 hours ago, HAAFPhot said:

It was believed back in the day (least within our Avn intel cell) that the things were so underpowered, transitional take offs and in the main landings were pretty normal and the UC deployed below a minimum airspeed. Might be something to do with that, or simply that locally they were in short supply and felt to be superfluous so not replaced, bit like the original engine cowl arrangement for the Westland Scout. More trouble that it was worth🙄

Have you seen a Hind performance at an airshow? Then of course they are rather large... and in hot and high conditions in Afghanistan performance for sure decreased...

Underpowered may be not the first thing coming to mind related to the Mi-24 though

 

 

I think I remember that the US Apaches had to remove their Longbow radar in Afghanistan for being underpowered...only British Rolls Royce powered Wah-64 could carry it routinely....

[spruecutter96]

Being an assault helicopter, I wouldn't have thought aerodynamics was an important factor for the designers. I know they produced an upgraded, experimental version which had the landing-gear permanently fixed in the deployed position (but I don't think that version ever reached production, however). 

 

In the hot-and-high conditions of Afghanistan, Russian pilots routinely used rolling take-offs, as previously stated. I've read that, if shot-down and captured, the Soviet crews suffered some truly horrible deaths at the hands of the locals. 

 

Cheers. 

 

Chris.  

Edited October 10, 2022 by spruecutter96
Correcting a typo.

[Steve McArthur]

The common configuration for retractable gear helicopters is to delete some or all of the doors. I started making a list of all the retractable gear helicopters missing doors and realized the list for all landing gear fully retracted and covered is a lot shorter:

 

1) Sikorsky S-76 (driven by marketing)

2) Sikorsky RAH-66 (driven by stealth)

3) ???

 

Most of the drag reduction is from getting the strut and tires out of the breeze and you save a little weight and maintenance deleting the doors and retraction mechanisms.  You really only go for the added weight and complexity of retractable gear if high speed and range are design goals and the Mi-24 was one of the fastest helicopters when it was introduced.  With all the stuff hanging from the nose of a Mi-24 the flow under the nose is not going to be all that smooth, so I'd guess they figured out there was no advantage to keeping the nose gear doors.

[Doom3r]

8 hours ago, spruecutter96 said:

Being an assault helicopter, I wouldn't have thought aerodynamics was an important factor for the designers. I know they produced an upgraded, experimental version which had the landing-gear permanently fixed in the deployed position (but I don't think that version ever reached production, however). 

 

In the hot-and-high conditions of Afghanistan, Russian pilots routinely used rolling take-offs, as previously stated. I've read that, if shot-down and captured, the Soviet crews suffered some truly horrible deaths at the hands of the locals. 

 

Cheers. 

 

Chris.  

 

Mi-35M has fixed landing gear and is produced in small quantities. I remeber few years back there was a video on Zvezda channel (the Russian MoD channel) about this version: they claimed that by making gear fixed they saved quite a bit of weight.

[dov]

Well, considering your information:

So I conclude that removing the rear front landing gear door:

The weight of the retractable gear is there anyway.

So maybe you reduce maintenance on the retraction mechanism of the door only.

The retraction of the front landing gear operates!

Drag is always a matter for every pilot in fighting operation.

Since just each advantage in speed can decide of survival or not.

In summery I can only admit that it makes no sense to me at all, to leave the rear door away.

Just in case there is a severe design fault that this door may cause accidents. In which way however.

A constant sucking airflow, which drives the door in open position for instance!

Happy modelling

[HAAFPhot]

On 10/10/2022 at 21:43, exdraken said:

Have you seen a Hind performance at an airshow? Then of course they are rather large... and in hot and high conditions in Afghanistan performance for sure decreased...

Underpowered may be not the first thing coming to mind related to the Mi-24 though

 

 

I think I remember that the US Apaches had to remove their Longbow radar in Afghanistan for being underpowered...only British Rolls Royce powered Wah-64 could carry it routinely....

Well I was guided by the MOD and yes I have seen the “unladen” performance of the early A and D models. But an air show, particularly with eastern bloc types, is never a good gauge of performance. We still hold the rotary speed record, but that was not set by a line squadron Lynx, nothing like. This said, at the time the Mujahadeen were taking the things out “hot and high” simply by shooting down at them, and again noted that if they ever came down to speeds associated with translation (10-14Kts IAS typically) then the UC popped down, landing or otherwise. The Hind remember is an incredibly old airframe that keeps going, but it could never be described as a pure gunship in much the same way as our Lynx or Scout couldn’t be because they too had a trooping capacity, although ours generally only carried reloads out to a FARP and you have to assume the Soviets did the same. Of course it also served to bolster morale in that downed crews could be recovered (nice to know in Afghanistan), a design feature carried on with the Havoc but only possible with the AH using rescue straps carried by the crews (or in the case of Jugroom fort pure bottle). The comment re Longbow is correct, and in fact would have afflicted the first 9 or so of our cabs as they were straight 64As and not the modified WAH with the RTM ECUs. This said, even then, the WAH still struggled with the environment. Many military helicopters start life as adequate, but development of equipment, weapons, DAS etc soon lead to a higher MAUM and performance suffers. Either by reduced limits, endurance or MAUM, or all of the above. This is often not as simple as adding a more powerful ECU as transmission, airframe, blades,systems will as likely need reinforcement to cope. The Sea king strake was one small stroke of genius but very rare. As I say, back at that particular time they were considered underpowered. Now, I am out of the loop so couldn’t say.

[HAAFPhot]

On 11/10/2022 at 07:08, Doom3r said:

 

Mi-35M has fixed landing gear and is produced in small quantities. I remeber few years back there was a video on Zvezda channel (the Russian MoD channel) about this version: they claimed that by making gear fixed they saved quite a bit of weight.

Makes sense and as likely more crashworthy. Better to auto with all 3 than 1 hanging. The A109 went this way. I don’t buy aerodynamic efficiency on an attack helicopter as an absolute priority as speed is often not a huge issue, although endurance is.

[HAAFPhot]

On 10/10/2022 at 22:14, spruecutter96 said:

Being an assault helicopter, I wouldn't have thought aerodynamics was an important factor for the designers. I know they produced an upgraded, experimental version which had the landing-gear permanently fixed in the deployed position (but I don't think that version ever reached production, however). 

 

In the hot-and-high conditions of Afghanistan, Russian pilots routinely used rolling take-offs, as previously stated. I've read that, if shot-down and captured, the Soviet crews suffered some truly horrible deaths at the hands of the locals. 

 

Cheers. 

 

Chris.  

Chris, I believe that the threat to downed crews was part of the reason the MI28 has a small cabin to grab individuals. 

[spruecutter96]

6 hours ago, HAAFPhot said:

part of the reason the MI28 has a small cabin to grab individuals. 

I had no idea about that. It makes a lot of sense.

 

Cheers. 

 

Chris.